Adenosine Deaminase Acting on RNA (ADAR) is a member of a gene family that is involved in site-selective RNA editing that changes adenosine residues to inosine. Three vertebrate ADAR gene family members, ADAR1, ADAR2,and ADAR3, have been identified. ADAR1 and ADAR2 form a stable enzymatically active homodimer complex and ADAR3is a monomeric, enzymatically inactive form.

Characteristics: These antibodies specifically bind to the identified antigens on influenza viruses. All of the antibodies are useful for ELISA and some of the antibodies are also useful for Western blot. The specificity of the various antibodies that have been characterized is as shown:

Wistar researchers have developed polyclonal and monoclonal antibodies (PAb 99Pst and MAbs 99D through 99I) that bind to BIN1, a novel tumor suppressor protein that interacts with and inhibits the oncogenic activity of the MYC oncoprotein. BIN1 is functionally deleted in carcinomas of the breast, colon, lung, liver and cervix and has been implicated in programmed cell death (apoptosis). Apoptosis is an active process of physiological cell suicide that is critical to normal tissue homeostasis but that does not function properly in tumor cells. Work aimed at defining the genetic control of apoptosis and understanding its dysfunction in cancer has centered on the MYC oncoprotein, because it can promote either cell proliferation or apoptosis. Wistar scientists theorize that BIN1 may activate or facilitate apoptosis, thereby overcoming MYC's malignant growth activity. The antibodies generated by Wistar scientists are useful for research aimed at understanding the role of the BIN1 protein in the genetic events associated with apoptosis.

Wistar researchers have identified a novel protein, BAP1, which is a nuclear-localized, ubiquitin carboxyl-terminal hydrolase that binds to the wild-type RING finger domain of the Breast/Ovarian Cancer Susceptibility Gene product, BRCA1. Murine Bap1 and Brca1 are temporally and spatially co-expressed during murine breast development and remodeling, and show overlapping patterns of subnuclear distribution. BAP1 resides on human chromosome 3p21.3 and rearrangements, deletions and missense mutations of BAP1 have been found in lung carcinoma cell lines and in primary breast tumor samples. BAP1 enhances BRCA1-mediated inhibition of breast cancer cell growth and is the first nuclear-localized ubiquitin carboxy-terminal hydrolase to be identified.

Analysis of the underlying genetic component of breast cancer localized the heritable component of this disease to a gene, the breast cancer susceptibility gene (BRCA1), located on chromosome 17 (at q21). As expected, the BRCA1 gene is mutated in the majority of heritable breast cancers and the mutations within the coding region occur throughout the gene with little apparent clustering. The majority of these mutations lead to shortened BRCA1 gene products, thus describing the need for a marker of the amino-terminus of the protein. Wistar scientists have isolated antibodies secreted by hybridomas derived from the immunization of mice with purified polypeptide representing a 100-amino acid segment of the amino terminus of the BRCA1 gene product. Hybridomas with restricted reactivities were selected, subcloned and the secreted antibodies have been tested for anti-BRCA1 reactivity in a variety of assays. The antibody demonstrates an extreme specificity to the BRCA1 gene product by immunoprecipitation analysis. The Wistar-developed antibody described herein provides an excellent tool for the identification of both the full-length and mutated (shortened) forms of BRCA1.

Scientists at The Wistar Institute have created monoclonal antibodies that react with the Wilms' tumor (WT1) protein. These antibodies can be used diagnostically in a variety of malignancies that over-express the WT1 protein. In particular, they can be used for distinguishing mesotheliomas from other tumors or nonmalignant conditions that affect the pleura. In addition, the antibodies may be used to monitor disease activity in acute leukemias.

The wt1 gene was originally identified as a candidate tumor suppressor gene by researchers investigating the causes of Wilms' tumor, a childhood kidney tumor. The gene codes for the WT1 protein, which has the structural features of a DNA-binding transcription factor. The WT1 protein has been shown to be over-expressed in a variety of tumors.

Three monoclonal antibodies have been developed, designated 6F-H2, 6F-H7, 6F-H17, and the isotype for each is IgG1.

The hybridomas producing these antibodies resulted from the fusion of spleen cells from mice immunized with a peptide comprising the N-terminal 173 amino acids of the WT1 protein and cells of the myeloma fusion partner P3x63AG8/653. This N-terminal region of the WT1 protein has little sequence homology to any other known protein. The resulting antibodies do not cross react with other transcription factors containing the zinc finger motif. Consequently, these monoclonal antibodies are more specific than either polyclonal or monoclonal antibodies to WT1 that have been produced by other researchers.

Nerve growth factor is important for regulation of development of sympathetic and sensory neurons and other neural crest-derived cell types. MAbs ME20.4 and ME82.11 bind to the low affinity NGFR of human origin. Using these MAbs, we have carefully defined the biochemical nature of the NGF receptor and its distribution among normal and transformed neural crest tissues.

Wistar scientists have developed two MAbs (designated 8 and 11) against bFGF (basic fibroblast growth factor), which is a major mitogen for cells of various embryological origin. It is important for development, tissue regeneration, cancer, and inflammatory diseases. Its detection is highest in activated tissues. In certain cancer such as melanomas, bFGF is an autocrine growth factor. Neutralization of its activity leads to cessation of growth.

Cell surface melanoma-associated antigens can mediate cell-cell or cell-substrate adhesion, signal transduction, proteolysis, or immune recognition and play a key role in determining invasive and metastatic competence of the tumor cells. MAb A32 binds to endothelial and melanoma cells and detects a 113 Kd cell surface adhesion receptor of the immunoglobulin supergene family. The Mel-CAM/MUC18 antigen is a cell surface molecule involved in heterotypic adhesion. The ligand for Mel-CAM/MUC18 has not yet been identified. Its characterization will be important for endothelial cell adhesion during inflammation.

The gene for the tumor suppressor protein p53 encodes a nuclear phosphoprotein that is altered by mutation or deletion in about 50% of human tumors. When single point mutations modify p53 structure and function, post-translational modifications of mutated p53 molecules are expected to interfere even more strongly with its function of controlling cell growth and division. The most prominent post-translational modification of p53 is phosphorylation at one or more of many sites along the protein. Wistar researchers developed a double-phosphorylated peptide that is phosphorylated at the Ser378 and Ser392 sites of human p53. This peptide was then used to generate a highly sensitive monoclonal antibody (mAb p53-18) to p53 protein. This antibody can be used to distinguish the phosphorylated from the non-phosphorylated forms of p53. Since sera from cancer patients preferentially label the double-phosphorylated p53 peptide, the mAb p53-18 may be useful in developing cancer diagnostics.

CD8+ T cells have been traditionally classified as cytotoxic lymphocytes. However, a number of studies have suggested that the CD8+ T cell population is in fact functionally heterogeneous. For example, research has demonstrated that cytotoxic or regulatory (suppressor) activities and an ability to release distinct cytokine profiles distinguish subsets within the CD8+ T cell population. Specifically, research has classified CD8+ T cells as Type I (producing IFN, GMCSF, and TNF) or Type II (producing IL-4, IL-10, GMCSF, and TNF).

Antibody: Wistar scientists have developed a monoclonal antibody designated C1.7 that recognizes a novel surface marker (p38) expressed on all NK cells and 50% of peripheral CD8+ T cells. The C1.7+ CD8+ T Cell subset has been shown to have higher cytotoxic activity and predominantly release a type I cytokine profile. The C1.7- subset has a lower cytotoxic activity and some of the cells may release a type II cytokine profile. On NK cells, C1.7 is a signaling molecule that when crosslinked, induces cytotoxic activity and release of cytokines.

Wistar researchers have developed monoclonal antibodies against five cell surface markers that are useful in the identification and characterization of human embryonic stem cells and monitoring their differentiation. Investigation of the function and expression of developmentally regulated cell surface antigens may yield clues to the control of cell differentiation, not only during embryogenesis but also during oncogenesis. These monoclonal antibodies bind to cell surface antigens SSEA-1 (stage-specific mouse embryonic antigen), SSEA-3, SSEA-4, TRA-1-60R, and TRA-1-81.